1. Field of the Invention
The present invention relates to methods and apparatuses for analyzing the solder plating solutions, and more specifically to methods and apparatuses for determining concentration of various components in both eutectic solder plating solutions and high lead solder plating solutions.
2. Related Art
In the production of electrical printed circuit board, it is common to electroplate the electrically conductive regions of the board with a tin-lead coating, commonly referred to as solder. Such a tin-lead coating facilitates the subsequent connection of electrical components, such as resistors, transistors, integrated circuits, and the like, to the printed wiring board. Moreover, the increasing use of integrated circuits has necessitated use of multilayer printed wiring boards having solder plated through-holes for electrically connecting circuitry on the various layers of the board.
High-lead solder is also used to connect controlled collapsible chip contact (“C4 chip”) to its substrate, for relieving thermal stress and providing a reliable contact between the chip and the substrate. C4 chips were intended for use in modules with low expansion substrates that minimize thermally generated stresses. These modules were often hermetically sealed to protect bare chips from the environment.
Eutectic solder solutions or high lead solder solutions commonly used for electrochemical deposition (ECD) of solder must be monitored in situ to insure optimal efficiency. Specifically, changes in the concentrations of inorganic components (such as acid, lead, and tin) and organic additives (such as polymeric non-ionic surfactant, brightener, and antioxidant) in such solder solutions must be determined during the solder plating process for accurate and precise process control.
However, conventional methods for determining component concentrations in solder plating solutions are complicated and unreliable, resulting in high error rates. Moreover, no automated, on-line solder analytical tools are currently available for automatic concentrations analysis of solder plating solutions, and most of the solder plating solution analyses are still conducted manually.
Moreover the final processing of highly complex and expensive microcomputer chips by solder plating demands rigorous control of the bath.
It is therefore an object of the present invention to provide methods for faster and more accurate determination of component concentrations in solder plating solutions.
It is another object of the present invention to provide automated, on-line analytical tools for automatic concentration analysis of solder plating solutions, and more preferably an integrated analytical tool for automatic determination of the concentrations of all the inorganic and organic components of a sample solder plating solution.
Other objects and advantages will be more fully apparent form the ensuing disclosure and appended claims.